The air is cleaner in Pennsylvania thanks to fracking, the state’s Department of Environmental Protection announced on Tuesday.

DEP released emissions data for the unconventional drilling industry, which includes shale gas drilling, also known as fracking. Pennsylvania is part of the Marcellus Shale formation, one of the country’s largest sources of natural gas.

“The data show that emissions from drilling represent a small fraction of air pollution in the state, which has gone down considerably since shale gas development began in earnest several years ago,” DEP Secretary Mike Krancer said in a statement.

Environmentalists are pushing tighter regulations for the controversial drilling practice, saying it pollutes air and water. But DEP’s data shows existing regulations are already doing their job.

“Natural gas is a domestic, abundant, clean-burning fuel source,” Krancer said, “and we have the regulations in place to assure that air emissions during drilling and transmission do not compromise the environmental benefit of natural gas as a fuel for electricity and transportation.”

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DEP submits emissions data to the U.S. Environmental Protection Agency every three years, and Tuesday’s release covers the period between 2008 and 2011. The data includes refineries, manufacturing plants, power plants, dry cleaners and cars, trucks and other vehicles.

Updated 2:55 p.m.:

The Marcellus Shale Coalition praised the DEP release, saying the gas industry is committed to reducing its environmental footprint and helping lower emissions.

“Our industry is driven by continuous improvement and technological advancements that further reduce the relatively minimal and short-term environmental footprint associated with safe, tightly-regulated natural gas development,” said MSC CEO Kathryn Z. Klaber in a statement. “And while these data focus on that small percentage of emissions that come from our operations, the increased use of clean-burning natural gas is proving critical in addressing and achieving improved air quality in Pennsylvania and across the nation.”